This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A067945 #24 Nov 01 2024 11:26:06
%S A067945 1,2,4,8,16,20,32,40,64,80,100,128,160,200,220,256,272,320,328,400,
%T A067945 440,500,512,544,640,656,800,880,1000,1024,1088,1100,1220,1280,1312,
%U A067945 1360,1600,1640,1760,2000,2048,2176,2200,2420,2440,2500,2560,2624,2720,3088
%N A067945 Numbers k that divide 3^k - 1.
%C A067945 Closed under multiplication: if x and y are terms then so is x*y.
%C A067945 The number (3^k-1)/2 is a term of this sequence if and only if k is a term. - _Thomas Ordowski_, Jul 25 2024
%H A067945 Charles R Greathouse IV, <a href="/A067945/b067945.txt">Table of n, a(n) for n = 1..10000</a>
%t A067945 Join[{1},Select[Range[3100],PowerMod[3,#,#]==1&]] (* _Harvey P. Dale_, Nov 01 2024 *)
%o A067945 (PARI) is(n)=Mod(3,n)^n==1 \\ _Charles R Greathouse IV_, Aug 01 2016
%Y A067945 Cf. A024023.
%K A067945 easy,nonn
%O A067945 1,2
%A A067945 _Benoit Cloitre_, Mar 05 2002